“To many, human-animal chimeras — animals that contain human cells — sound like the stuff of nightmares. If you can picture a frog with a human head, a monkey with human vocal chords or a dog with opposable thumbs, you can see why some people want to put the brakes on any sort of scientific experiment that mixes cells from different species.”

But the reality is far less alarming, he writes:

Picture instead a pig that produces human insulin or a mouse getting chemotherapy for its human cancer cells. But inter-species blends still raise concerns, even among scientists. The British Academy of Medical Sciences just released a report calling for new rules to avoid ethical missteps. The report expressed particular concern over several types of research, including anything that would implant human brain cells into animals. During a comment period, some members of the public worried that such experiments could give animals human memories.

That sounds like a great premise for a science fiction short story: The mouse who remembers growing up in a dysfunctional family in the suburbs. But even the academy acknowledges that an animal with human thoughts or consciousness is pretty far-fetched. Indeed, many of the fears surrounding chimeras are based on a misunderstanding of the real-world applications.